Short-cut for "cursor to selected"
Bring up your snap menu with Shift+S.
Hover your mouse over 'cursor to selected', and then click on it with the RMB . You will see an option to either add or change the keyboard shortcut.
Hover your mouse over the box that appears, (it should tell you to press a key), and then press the desired shortcut one key at a time while still holding them down to create your new shortcut.
Make sure to save your new shortcut as defaults by going to user preferences by pressing Ctrl+Alt+U,  and then save user settings.


In 2.8 and later, you can add a new shortcut to Quick Favorites which will give you a small menu with the keyboard shortcut Q
Simply RMB  and select Add to Quick Favorites from the choices that appear.